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a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1790180898; bh=zRx/KbW622lc9oNGjU0HBG2ucuK06pk04r2BRU2Rs4k=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lk4iTPb2Y7uutncKN/+j8ht7tPnRTZ6o43sCv1igw+EdAbkap5LleY6qa51nPpFa6 oFrn4wb6BHxvCgReQsk80Yv5Gq+s/5rQRHwDalOdArIoH0GTefNuq6TyY2rgXsVOhS gNMu/nMv3dX8EIbRcFZTUFCIb4A9JF6t3XJZs7Dw= Message-ID: <5cbe0bde-47d8-41ca-b244-bc0329d0d066@linux.microsoft.com> Date: Wed, 23 Sep 2026 09:28:54 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v7 02/13] mm: Add an allocator for CoCo shared memory To: Jason Gunthorpe , "Aneesh Kumar K.V" , mhklinux@outlook.com Cc: Catalin Marinas , linux-coco@lists.linux.dev, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, Andrew Morton , christian.koenig@amd.com, Joerg Roedel , Marc Zyngier , Marek Szyprowski , Robin Murphy , Steven Price , Sumit Semwal , Suzuki K Poulose , Thomas Gleixner , Will Deacon , dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org, linux-mm@kvack.org References: <20260921144847.501151-1-aneesh.kumar@kernel.org> <20260921144847.501151-3-aneesh.kumar@kernel.org> <20260923130611.GF1540250@ziepe.ca> <20260923152124.GG1540250@ziepe.ca> Content-Language: en-US From: Kameron Carr In-Reply-To: <20260923152124.GG1540250@ziepe.ca> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 7a679j8ytzn6geptfcum5zuxwzsekcgw X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 5A44280003 X-HE-Tag: 1790180948-124352 X-HE-Meta: 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 w1Ob0pS6 4z9lcLV9BQ39KjRdVjyldtQNKpPfWZ0DjEwhu80ij9nNnp9KLEwb4CX+scZy9tFpuyFkepA17ufWB8iAUOUdR0rUS9/RuB7uJ50x8UWkwd1sF8EOOyT2tSKpOxQTSa1aF3l6AQMpa+EFCfqOKlCZUy121dK8V+npYknv92BATivHApf9/vSVvm+NfA1oMvNyouX60pHl9UqJgowFj81M/Ie34s8E1qedNNBcaWp+ulnUs6p7aFh2GzWmLWkwKqL4qwXQXlnBFOadg73Eipxhxw9VnE6WuLKnk3Gln6z0b2UVnNRGaVKtZNxyfzcyag5oXhuIve2R3GK3U6ivp3WaZOEBi2PVRjlVwgKuhIZwlUxiwZmU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/23/2026 8:21 AM, Jason Gunthorpe wrote: > On Wed, Sep 23, 2026 at 08:28:57PM +0530, Aneesh Kumar K.V wrote: > >> I'm also considering requiring the address passed to cc_make_shared() to >> be in the linear map. This is currently required by both TDX and CCA, >> while AMD SNP appears to support vmalloc addresses. The only user of >> that vmalloc support is Hyper-V VMBus GPADL setup >> (vmbus_establish_gpadl()). How should the generic CoCo shared-memory >> allocator handle this? > > vmbus_establish_gpadl() is the the same wrong abstraction as the arch > code. Get rid of it and use vmbus_establish_gpadl_caller_decrypted(): > > pdata->recv_buf = vzalloc(RECV_BUFFER_SIZE); > if (!pdata->recv_buf) { > ret = -ENOMEM; > goto fail_free_ring; > } > > ret = vmbus_establish_gpadl(channel, pdata->recv_buf, > RECV_BUFFER_SIZE, &pdata->recv_gpadl); > > > So you made an allocator that returns folios, now you just need to > use that allocator to implement a kvzalloc wrapper. ARM can call vmap > on decrypted memory with pgprot_decrypted(), right? > > Or maybe this can use vmbus_alloc_buffer(), it already does it. Michael Kelley recently proposed [1] moving all ring buffer allocations to use vmbus_alloc_buffer(). If we move forward with this, it should remove the dependency on vmalloc support. [1] https://lore.kernel.org/all/SN6PR02MB4157B71CAC1433B04B92B700D4832@SN6PR02MB4157.namprd02.prod.outlook.com/ Kameron